Coherent optical systems involving lasers are capable of rapidly manipulating great blocks of data at high data rates. Such coherent data systems can perform mathematical operations, data reduction, pattern recognition, and other operations on two-dimensional blocks of data. Devices for converting electrical data signals to two-dimensional coherent optical data arrays are useful as input devices to coherent optical data systems. Some of these devices, referred to herein as block data composers, have both transducing capability and memory capability. Matrix-type block data composers of PLZT crystals have been employed in the prior art in strain biased modes of operation and in scattering modes in which light passing through the crystal is scattered into different sizes of solid angles at the output.
In some of the strain-biased electro-optical storage devices of the prior art, birefringent properties of PLZT crystal have been employed. To enhance the birefringence phenomenon, a mechanical strain bias has been produced in the crystal by bonding the crystal to a transparent plastic plate that is much thicker than the crystal, and bending the plate in a holding jig to subject the crystal to tension along an axis parallel to its major surfaces. This technique, while satisfactory for strain biasing a single crystal memory element or a small array of elements on a single crystal, is troublesome when employed to strain bias a large matrix of data storage locations on a single crystal. Variations in the strain applied to different areal portions of the crystal result in greatly different birefringence effects at the different portions, and inhomogeneities and differences in thickness of the crystal from place to place on its relatively large surface necessitate different amounts of strain bias which cannot be provided simultaneously by the bending jig.